Well first Geralt is definitely high level (I'd say 15's about right).
ALCHEMIST was pretty much modelled on the Witcher (although I think Magus fits pretty well the way I played in the first game at least).
I'll come check what people have said when I have more time.
(Without really thinking I'd probably go Half-Elf Alchemist with Racial Bastard-Sword Proficiency. Starting Stats something like 16 14 14 10 14 10 ... I'd tweak that more, but again, I'll come back when I have more time.)
If we were doing 3.5, I would pick Grey Guard all the way.
Since this is Pathfinder, My first thought would be Ranger(martially skilled, minor casting, excellent tracker). As Mr Charisma mentioned, Alchemist gives you the most options like the witchers potions, mutagens, bombs(look, even named the same!) and oils. Vivisectionist Alchemist removes your bombs but combat wise makes you a bit more like some of the optional witcher abilities.
Multiclassing would be a good option too but I can't decide what sort of class spread to go with.
I'd probably start with base stats of 15, 13, 14, 15, 12, 7 and then cheat a bit, declare him Azlanti, and get him the +2 to all stats.
I was thinking about that last night. Now I never really played the games so only know the books. So while the alchemist might be based off the witcher I never seen him throw a bomb. With that in mind I kinda think a investigator using a bastard sword might be pretty comparable.
Nah, he throws bombs. The problem is he also has spells. I'm not sure how to get spells on an alchemist without Multiclassing and tanking your other features. I suppose you could use racial magic?
I think it will help to decide which Geralt build you are using. In game you can have drastically different characters based on what skills you take and school of armor you use. A bear or cat would be full BAB, for example. Bear would be Barbarian or Bloodrager. Cat would be Rogue or Ranger. Gryphon would be something like Magus. And Alchemist has already been mentioned.
After mulling it over, I actually think the Grenadier Alchemist would be the best single class for doing it all. Bombs, mutagen, and extracts are all obvious. The Grenadier also gets martial weapon profiency, and the ability to apply items like alchemist fire or holy water to their sword mid combat, which represents oils. And directed blast can be used for Igni.
Your other signs should be covered with the right combination of extracts and discoveries. Force bombs can be Aard. Confusion bombs can be Axii. Quen can be stuff like Shield or Shock Shield. Not sure on Yrden but I'm sure there's an option somewhere.
All you are missing is Witcher senses like a Ranger or Inquisitor might have but that should be easy to remedy between racial features and extracts. Best of all, this build is flexible will let you tailor your feats and discoveries to match whatever Geralt fits your whims as he levels up, much like the video game.
Ah the video game, as I mention my knowledge there is slim. In the books her knows them but it is more a extension of passive knowledge (ie my spacecraft is high so I know a couple orison) but overall I'm trying to remember a story her really uses those. Typically if he knows trouble is coming he downs some potions to prepare. I'm sure the grenadier would work in place of the blasting spells. (Honest I habe the games someday I'll play them) I still stand by a half elf investigator that took the exotic bastard sword. Her might not be as flashy but he fits the novel version. Really though many classes could fit hook
Pretty simple, if you were going to build Geralt of Rivia from the Witcher series how would you build him? Only rules are that it should be a 20 point build and the build should max at level 15.
Just FYI, there's at least 7 other threads with witcher conversions. Maybe searching for those threads will help with your goal.
Ah the video game, as I mention my knowledge there is slim. In the books her knows them but it is more a extension of passive knowledge (ie my spacecraft is high so I know a couple orison) but overall I'm trying to remember a story her really uses those. Typically if he knows trouble is coming he downs some potions to prepare. I'm sure the grenadier would work in place of the blasting spells. (Honest I habe the games someday I'll play them) I still stand by a half elf investigator that took the exotic bastard sword. Her might not be as flashy but he fits the novel version. Really though many classes could fit hook
If you're a fan of the novels (as I am), you will find the Witcher 1 to be... weird. It plays like bad fanfiction - literally, it chops up bits of the short stories and novels and pastes them together into quests.
The Witcher 2 is better since it has an original plotline, but it still feels a bit off. The Witcher 3 is freakin' awesome, but still feels a bit odd given the information presented in the novels. But I am willing to forgive it because Ciri.
Anyway...
Alchemist was indeed inspired by the Witcher, but as noted, most likely by the video game version. There are some interesting homebrew Witcher classes I've seen online. One of them was a Ranger archetype, if I recall correctly, that used the different weapon styles to simulate the various Witcher schools and replaces ranger spells with a series of low-power SAs usable at will (for signs). That's the one I used in my own Witcher game (possibly with some modifications - can't remember for sure).
On further further reflection, Ranger is actually a bad choice. Rangers pick a couple monster types to specialize in slaying. A big part of the Witcher lore, training, and mechanics revolve around knowing EVERY monster, and having the tools to handle them based on that knowledge. Slayer would be better fit than Ranger.
If Alchemist isn't your jam, then you really want an Investigator or Inquisitor. Both get sky high monster knowledge scores and solid buffs. Investigator with mutagen and extracts obviously better represents the alchemy, and swift poison could probably be a passable oil representation. Inquisitor, maybe of the Sanctified Slayer archetype, requires a bit of reflavoring but gets spells to simulate signs and self buffs to simulate other stuff. Bane is a pretty awesome version of oils and general Witcher weakness knowledge. Tracking, Monster Lore, and Studied Target/Judgement round it out to be an all around excellent power house.
My vote would still be for Ranger, as a Witcher really needs full Base Attack Bonus as they are killing machines. There is also an Occultist Archetype that came out that had Full BAB as well that could work.
Homebrewed Witcher (Ranger) Archetype:
Haven't had a chance to test it yet. *Shrug* Might use it in Kingmaker.
My vote would still be for Ranger, as a Witcher really needs full Base Attack Bonus as they are killing machines. There is also an Occultist Archetype that came out that had Full BAB as well that could work.
Homebrewed Witcher (Ranger) Archetype:
** spoiler omitted **
Haven't had a chance to test it yet. *Shrug* Might use it in Kingmaker.
If we are looking at the games though a Witcher can be built to barely use the sword in comparison to their magic, and the Ranger (sans homebrew) misses a lot of iconic abilities if you are trying to get stuff across the board. Slayer would do a pure melee Cat school Witcher better, and the rage of a Barbarian or Bloodrager is a pretty bang on for the Adrenaline amping of the Bear School. Bloodrager even gives you some Signs to tack on, and various rage powers could simulate mutagens. Also, full BAB isn't especially a requirement for a class to be a killing machine in pathfinder.
Let's look at the Ranger's iconic class features.
Favored Enemy: Already covered, EVERY enemy is a favored enemy to a Witcher.
Track: This one actually works but isn't hard to get from other classes.
Wild Empathy: Has Geralt ever worked with a non-sentient animal beyond Roach?
Combat Style: Witcher's already use the least feat intensive style in pathfinder, so you don't especially need this.
Endurance: Sure, whatever.
Favored Terrain: A Witcher is equally comfortable hunting monsters through the sewers, the woods, or a crowded town. Most of the wilderness features of a Ranger aren't atually very Witcher-y.
Hunter's Bond: Witcher's tend to be lone operatives.
Spells: Cool, but the spell list is lacking in things to simulate both spells and alchemy, so it's almost irrelevant.
Woodland Stride: See Terrain.
Swift Tracker: Fitting, but see Track.
Quarry: Also good, but I reckon you can do this with Slayer talents or other abilities just as well.
Evasion: Good enough, but hardly unique.
Camouflage: Aside from being terrain specific, I dunno that Witchers are especially stealthy. I guess Cat School had some assassination roots, but again, Slayer or Rogue can do that.
I'm sure you can get closer using archetypes, but I question why you wouldn't just start with one of 7-8 other classes that fit better.